The present invention relates to a method for measuring three-dimensional spatial magnetic field distributions, which is useful for measuring a high magnetic field distribution in a small spatial region such as a leakage magnetic field of a magnetic head.
In magnetic recording, since the leakage high frequency magnetic field distribution of a micron order in the neighborhood of the gap of a magnetic head is a factor determining recording/reproduction characteristics, with increasing recording density and improvement in the quality in recent years, it becomes more and more inevitable in the development of magnetic heads to take into account the three-dimensional spatial leakage high frequency magnetic field distribution. Further, in recent years, attention is paid to microscopic dynamic response of the magnetic domain structure in thin film magnetic substances and it is thought that the three-dimensional measurement is necessary also for evaluating it.
As a method for measuring the magnetic field distribution of micron order, recently a method, so-called electron beam tomography, has been proposed, by which the magnetic field distribution is reconstructed three-dimensionally by the tomographic method, starting from the magnitude of deviation of an electron beam after the passage through the magnetic field region, using the deviating action due to the Lorenz force of the magnetic field acting on the electron beam, and computer simulation results on a simple model have been reported ("Evaluation of Three-Dimensional Micromagnetic Stray Fields by Means of Electron-Beam Tomography", IEEE Trans. Magn., MAG-21, 5, pp. 1593, 1594 (1985)).
By the method of the electron beam tomography relating to the proposition described above, in order to divert the linear reconstruction method used for the X-ray CT (computer tomographic method), the Trajectory of an electron in the magnetic field is approximated by a straight line.